1. Field of the Invention
The present invention relates to a stent delivery system, a stent placement method, and a stent attachment method.
2. Description of Related Art
A procedure known as “drainage” is sometimes performed in the case of bile duct stricture formation. In this procedure, a pusher catheter is used to insert a stent with a through hole into the stricture site, with the stent then retained at this position. A flap is provided at either end of the stent so as to open, thereby reducing movement of the stent following placement.
In order to enable recovery in the case where the inside of the stent becomes occluded over time, part of the stent is pulled out into the small intestine. However, when the stent is positioned in this way, a communication between the small intestine and the bile duct is continually maintained via the stent. As a result, food can flow from the small intestine into the bile duct, and thereby clog the stent. In addition, if coliform bacteria ascend, this can result in formation of a biofilm inside the stent which can cause occlusion.
Stents have been therefore developed in which occlusions are prevented and the stent can be retained for a long period of time by inserting the entirely of the stent into the bile duct. The function of the papilliary sphincter is preserved, preventing the flow of food or coliform bacteria into the stent. In order to facilitate percutaneous endoscopic recovery, this stent has a narrow and long grip piece attached to on the base end portion of the stent which is disposed to the duodenal side, and which is designed to be grasped with forceps or the like.
However, when placing the above-described stent using the conventional stent delivery system, it is necessary pull back the front end of the endoscope from the duodenum toward the stomach in order to expel the grip piece from within the catheter after placement of the stent. During this process, interference can occur between the channel or standing base of the endoscope, and the grip piece, so that there is a risk of catching therebetween.
Further, as shown by the arrow in FIG. 41, the papilla DN disappears from the field of view of endoscope 100 when the endoscope 100 is pulled back toward the stomach. As a result, it becomes difficult to confirm using endoscope 100 whether or not the front end of the grip piece 101 has definitely been expelled out into and positioned within the duodenum. In order to recheck the duodenum via the endoscopic image, the front end of the endoscope 100 must be inserted into the duodenum. Further, this operation becomes even more difficult if the front end of the endoscope 100 has been pulled back into the stomach.
Thus, it is not easy to confirm whether or not the grip piece has been retained at the appropriate position, leading to such problems as an increase in the number of procedure steps and an increase in the duration of the procedure.
The present invention was conceived in view of the above-described circumstances, and has as its objective the provision of a means for enabling the grip piece of the stent to be easily expelled into the duodenum while confirming the duodenal papilla using the endoscope, without having to pull the end of the endoscope from within the duodenum back toward the stomach.